DESCRIPTION: Prenatal exposures to endocrine disruptors, including several organochlorine pollutants, have been linked to developmental abnormalities and neurobehavioral deficits, but causal associations and dose-response relationships are unclear. A birth cohort of 182 children was formed in 1994 at the Faroe Islands, where increased exposures to these substances mainly originates from consumption of pilot whale blubber. This North Atlantic fishing community is unique and highly suitable for prospective population-based studies, because exposure levels vary more than 100-fold due to differences in dietary habits. Stored maternal serum from week 34 of pregnancy will now be used to characterize the endocrine disruption potential expressed as activation of the estrogen receptor and the Ah receptor. Postnatal exposure levels will be determined from analysis of serum collected from the children. Exposures to methylmercury and essential nutrient status will also be determined. Data on growth and development from annual examinations up to age 5.5 years are available and will now be supplemented by examinations at ages 7 and 9 years, when advanced testing will be applied to assess sexually dimorphic behaviors, domain-related neurobehavioral function, serum hormone concentrations, and developmental markers of early puberty development. Modern statistical methods will be used to determine whether these outcome variables are associated with estrogen, thyroid, or Ah receptor abnormalities and specific contaminant exposures prenatally or postnatally.